Submission #667474

#	Time	Username	Problem	Language	Result	Execution time	Memory
667474		Soul234	Mergers (JOI19_mergers)	C++14	100 / 100	562 ms	95588 KiB

mergers

#include<bits/stdc++.h>
using namespace std;

void DBG() { cerr << "]\n"; }
template<class H, class... T> void DBG(H h, T... t) {
    cerr << h; if(sizeof...(t)) cerr << ", ";
    DBG(t...);
}
#ifdef LOCAL
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif // LOCAL

#define FOR(i,a,b) for(int i = (a) ; i<(b) ; i++)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for(int i = (b)-1 ; i>=(a) ; i--)
#define R0F(i,a) ROF(i,0,a)
#define each(e,a) for(auto &e : (a))
#define sz(v) (int)(v).size()
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define pb push_back
#define tcT template<class T
#define nl "\n"
#define fi first
#define se second

using ll = long long;
using vi = vector<int>;
using pi = pair<int,int>;
using str = string;
using db = long double;
tcT> using V = vector<T>;
tcT> using pqg = priority_queue<T,vector<T>,greater<T>>;

void setIO(string NAME = "") {
    cin.tie(0)->sync_with_stdio(0);
    if(sz(NAME)) {
        freopen((NAME + ".inp").c_str(),"r",stdin);
        freopen((NAME + ".out").c_str(),"w",stdout);
    }
}

tcT> bool ckmin(T&a, const T&b) {
    return b < a ? a=b,1 : 0; }
tcT> bool ckmax(T&a, const T&b) {
    return b > a ? a=b,1 : 0; }

const int MOD = 1e9 + 7;
const ll INF = 1e18;

struct DSU {
    vi e;
    void init(int N) {
        e.assign(N, -1);
    }
    int find(int x) { return e[x] < 0 ? x : e[x] = find(e[x]); }
    bool join(int a, int b) {
        a = find(a), b = find(b);
        if(a == b) return false;
        e[b] = a;
        return true;
    }
} dsu;

const int MX = 5e5+5;

int N, K;
vi adj[MX];

int par[MX], dep[MX];

void dfs(int u, int p) {
    each(v, adj[u]) if(v != p) {
        dep[v] = dep[u] + 1;
        par[v] = u;
        dfs(v, u);
    }
}

void mergecc(int a, int b) {
    a = dsu.find(a), b = dsu.find(b);
    while(a != b) {
        if(dep[a] < dep[b]) swap(a,b);
        dsu.join(par[a], a);
        a = dsu.find(par[a]);
    }
}

vi lst[MX];

pi eds[MX];

int deg[MX];

void solve() {
    cin >> N >> K;
    dsu.init(N+5);
    F0R(i, N-1) {
        int u, v;
        cin >> u >> v;
        eds[i] = {u, v};
        adj[u].pb(v);
        adj[v].pb(u);
    }
    dfs(1, -1);
    FOR(i,1,N+1) {
        int col;
        cin >> col;
        lst[col].pb(i);
    }
    FOR(i,1,K+1) {
        FOR(j,1,sz(lst[i])) {
            mergecc(lst[i][0], lst[i][j]);
        }
    }

    F0R(i, N-1) {
        int u = dsu.find(eds[i].fi), v = dsu.find(eds[i].se);
        if(u != v) {
            deg[u]++;
            deg[v]++;
        }
    }
    int ans = 0;
    FOR(i,1,N+1) if(dsu.find(i) == i && deg[i] == 1) ans++;
    cout << (ans+1)/2 << nl;
}

int main() {
    setIO();

    int t=1;
    //cin>>t;
    while(t-->0) {
        solve();
    }

    return 0;
}

Compilation message (stderr)

mergers.cpp: In function 'void setIO(std::string)':
mergers.cpp:40:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |         freopen((NAME + ".inp").c_str(),"r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mergers.cpp:41:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |         freopen((NAME + ".out").c_str(),"w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 24 / 24
• Subtask 3: 14 / 14
• Subtask 4: 22 / 22
• Subtask 5: 30 / 30